Generate a crystal structure using GGen

Generate a single candidate crystal structure for a requested formula with exact stoichiometry (e.g. SiO2 or Fe2O3). GGen chooses or validates a compatible space group, samples candidate structures, relaxes them, and returns the best result as a CIF file. Use this when you already know the target composition. To scan across stoichiometries in a chemical system (e.g. Fe-Mn-Si), use Explore a chemical system with GGen instead.